Machine for boring tapering holes



May 1, 1923. Q Q 1,668,119

C. D. M ARTHUR MACHINE FOR BORING TAPERING HOLES Filed April 9. 1927 2 sheets-sheet 1 Q '6 3H 11 g 17 6- f 12 E0 1 10 1b 6 1e 9 INVENTOR v 36L WW.QTM KM May 1, 1928. 1,668,119

C. D. M ARTHUR MACHINE FOR BORING TAPERING HOLES Filed April 9. 1927 2 Sheets-Sheet '2 Patented May' 1, 1928.

CHARLES D. ,McARTI-IUR, 0F PITTSBURGH, PENNSYLVANIA.

MACHINE FOR BORING 'I APERING HOLES.

Application filed April 9,

The invention relates to a machine for boring tapering holes. It has for its principal objects the provision of an improved machine for accomplishing the function stated, which can be operated with great rapidity and precision to give quantity pro duction at a low cost; which is simple in construction; and which can be bililt and maintained at a low cost. ;()ne embodiment of the invention is shown'in the accompanying drawings, wherein: t I

Figure 1 is a plan iew (slightly in perspective) with the parts in the positionoccw pied after the tool'is withdrawntrom the work, the work being shown in section to t showthe character of the hole bored. Fig. 2

is a partial plan view showing tlieposition of the parts when thehole is being bored.

an a side elevation (slightly in perspective) of the parts in the position of Fig. 1. Fig. 4 iS an end elevation with thedrill in eiipanded position, and Fig, 5 is an elevation of the drill end in contracted position.

Reterririgto the drawings, 1 is a supporting lt'rame or table for the machine, and 2 is the work table supported bymeans of the guide bars 3, 3, which have the clips 3" slidinglye engaginghthe upper surfaces, of the b rsja io ming a part of the supporting frame 1. The bars 3,. 3-are rigidly secured at their 'for'ward ends to the table 2 b v means of the members 3*, and are connected at their other ndsby thetransverse bar 4:, Journaled in the framel is the hollow work spindle 5, which" releasably holds the tool bar or shank 6 of the tool. and'is driven-by the pulleys fi ando", 5being a loose pulley. Thetool comprises the flat center cutter 7, and the tw'oside cutters-8, 8, having laterally ezit'eiidirig ends-Q, 9 secured rigidly in the forward endsof the links 10, 10; The links 10; 10 are pivoted adjacent their forward ends at 1-1," 11, upon the fcross head 12 integral with the forward endot the tool shank 6., The center cutter 7 fits removahly in a socket in the'end of the shank 6, being held 'inyposition by means of'the set' screw 13. This permits of the removal of the cutter for replacement ors'liarpening, or to substitutea cutterof difierent width; t M i y The rear ends of the links 10, 10 are'pivOt ally connected at 14,14 to the Links 15, and such links are in turn pivoted at their rear ends at 16, 16 to the cross head 17 integral with a collar 18, which is rfreely In ofperation, w

1927. Serial No. 182,330.

shank 6. This is accomplished by means of the forked lever 23, pivoted on a rod 24, secured in a bracket 24, carried by the frame of the machine. Intermediate its ends, the lever ispivotally connected to the sides of the (lisc'22 by meansof the screws 25, 25. 'ljhe'lever is operated, when the work table n'loves to the left from the position of Fig. 3, by means of the arm 26 carried by't-he work table, and provided with the adjustable eng'aging member 27. This member has a pair of ods '28, 28 projecting through the headf29 0t thearnr26,and such rods are clamped in. positioh ljly set screws 30. The position of the member 27 determines the time at which thesido' cutters are caused to begin their spreading movement to cut the taper for the holebeingbored, I y y t ith the parts in the'position .0 Figs.-1and 3, the" rotation of the tool shank and the" pairs of links 10, 15, and 10, 15,'c ausesthe links to swing out'to the positon' shown by' centrifugal torce,thus

holding the side cutters 8,8 in tightly against the center cutter 71 \Vith the cuttersin this position (seefFim 5),di1ly the center cutter engages thej wor c, when the work table is. moved to the'left'trom the positioh of Figs. 1 and 3. As a result, a hole A cut having straight sides (Fig I) as long as this condition obtains. hen the table2 moves to the left far enough to calise the member 27 to engage the lever 23, a furtl'ier Vinovem ent of thetable swings the lever to the left, thus moving the' collar 18 to the left and withit the links 15, 15, thus causingthe side cutt'ers 8, 8fto spread. fllhis spreading movement continues'until the collar 18strikesthe collar 20,and (.luring this period, theex panding side'cuttelrsiJcut the tapering portion B (Fig. 1) of the holei the parts at this time occupying the position shown in Fig. To withdraw the tool, the work table2 is movedtothe right, andduringthe period of withdrawal, centrifugal force spreads the links thus causingtlie cuttersi8, 8 to approach the center cutter, so thatv the side cuttors are free from the walls of the hole during the withdrawing movement.

It will be seen that the movements'of the side cutters are automatic during the boring and withdrawing operations, and that the length of the straight out portion A of the hole is regulated by the position of the member 27, the length of the taper portion B and the extent of the taper being governed .1 by the position of the collar 20, which may be adjusted to suit requirements. The di ameter 'of the. straight portion of the hole may be varied by changing the center cutter 7, while the position of the two stop collars 20 and 21 regulates the size of the taper portion of the hole, so that taper )ortions of different diameters to correspon to different size-'5 of center tools, may be bored by the side cutters without changing such cutters. By shifting the two collars to the left, the diameter of the taper portion of the hole is increased. The side cutters are made removable from the links 10, 10 so that they may be readily removed for resharpening or replacement.

. What I claim is:

1. In combination in a machine for boring tapering holes, a work table, and a machine support, one of which is movable toward the other, a driven tool bar mounted for rotation in said support, a centerboring tool carried thereby, a'pair of links pivoted adjacent the forward end of the bar, and each carrying a side cutting tool, a second pair of links pivoted to the rear ends of the first links, acollar movable longitudinally of the spindle and having pivotal engagement with the rear ends of said second pair of links, a pair of stop members mounted 'on the spindle for longitudinal adjustment thereof, adapted to limit the movement of the collar in both directions, and means operated by the movement of approach of the work table and machine support for moving the collar longitudinally of the spindle and causing the spreading of the side cutters.

2. In combination in a machine for boring tapering holes, a work table, and a machine support, one of which is movable toward the other, adriven tool bar mounted for rotation in said support, a center boring tool carried thereby, a pair of links pivoted adj acent the forward end of the bar, and each carrying a side cutting tool, a second pair of links pivoted to the rear ends of the first links, a collar movable longitudinally of the spindle and having pivot-a1 engagement with the rear ends of said second pair of links, a pair of stop members mounted on the spindle for longitudinal adjustment thereof, adapted to limit the movement of the collar in both directions, and means operated by the movement of approach of the work table and machine support for moving the collar longitudinally of the spindle and causing the spreading of the side cutters, the said links being arranged so as to move away from the tool bar by centrifugal force, when the tool bar is rotated, causing said collar to engage the forward stop member and the side outters'to move to closed position.

3. In combination in a machine for boring tapering holes, a work table, and a ma chine support, one of which is movable toward the other, a driven tool bar mounted for rotation in said support, a center boring tool carried thereby, a pair of links pivoted adjacent the forward end of the bar, and each carrying a side cutting tool, a second pair of links pivoted to the rear ends of the first links, a collar movable longitudinally of the spindle and having pivotal engagement with the rear ends of said second pair of links, apair of stop members mounted on the spindle for longitudinal adjustment thereof, adapted to limit the movement of the collar in both directions, a lever for moving said collar to the rear, and a member carried by the worktable and adapted to engage said lever and cause its movement after the-movement of approach between the work table and machine sup-- port has progressed a predetermined distance.

' al. In combination in a machine for boring tapering holes, a work table, and a machine support, one of which is movable towardthe other, a driven tool bar mounted for rotation in said support, a center boring tool carried thereby, a pair of links pivoted adjacent the forward end of the bar, and each carrying a side cuttin tool, a second pair of links pivoted to the rear ends of the first links, a collar movable longitudinally of the spindle and having pivotal engagement with the rear ends of said'second pair of links, a pair of stop members mounted on the spindle for longitudinal ad justment thereof, adapted to limit the moveing tapering holes, a work table, and a machine support, one of which is movable toward the other, a driven tool bar mount ed for rotation in said support, a center boring tool carried thereby, a pair of links pivoted adjacent the forward end of the bar, and each carrying a side cutting tool, a second pair of links pivoted to the rear ends of the first links, a collar, movable longitudinally of the spindle and having swivelled relation with the rear ends of said second pair of links,a pair of stop members mounted on the spindle for longitudinal adjustment thereof, adapted to limit the movement of the collar in both directions, a lever pivoted to the machine support above the tool bar and to the collar therebelow, and a member carried by the work table and adapted to engage the lower end of said lever and cause its movement after the movement of approach between the work table and machine support has progressed a predetermined distance. I y

6. In combination in a machine for boring tapering holes, a work tab1c,and a machine support, one of which is movable toward the other, a driventool bar mounted for rotation in said support, a center boring tool arried thereby, a pair of links pivoted adjacent the forward end of the bar, and. each carrying a side cutting tool, a second pair of links pivoted to the rear ends of the first links, a collar movable longitudinally bf the spindle and having pivotal engagement with the rear ends of said second pair of links, a lever for moving said collar to the rear, and a member carried by the work table and adapted to engage said lever and cause its movement after the movement of approach between the work table and machine support has progressed a predetermined distance.

In testimony whereof, I have hereunto subscribed my name this 8th day of April,

CHARLES D. MCARTHUR. 

